1. Field of the Invention
The invention relates to a device for sharpening a blade of a manual cutting tool, in particular a knife, comprising a support which is provided with a cut-out, sharpening elements being placed opposite each other and in a staggered arrangement in the region of the cut-out, being mounted so as to rotate about shafts which are fixed to the support and being provided with means for returning into position so as to define a sharpening zone which is variable in accordance with the position of the blade of a tool between the sharpening elements.
2. Brief Description of the Related Art
Devices of this type are used in the food-processing industry and in particular in the meat industry in order to reshape the edge of the knives used in a simple and rapid manner. Taking into account the speeds of production lines and the harsh environment encountered in these industries, owing, for example, to the ambient humidity and grease, it is necessary to have sharpening devices which are easy to use, clean and maintain and which are robust.
U.S. Pat. No. B 5,655,959 discloses a sharpening device which comprises a plate which supports two shafts on which curved shanks are mounted so as to freely rotate. These shanks are arranged at the sides of a cut-out, in this instance, two at one side and the third at the other side, so as to intersect with each other. They are provided at one end with an ancillary component which forms a counterweight. Cams which are located below the shanks in the region of the counterweights allow the return force to be adapted. It should be noted that one of the counterweights has a different mass from those of the other two counterweights. In this instance, the rod which carries this counterweight acts as a blade guide. Rods are arranged so as to guide and form travel end stops for the shanks. The zone which is located between the shanks which intersect forms a sharpening region. The knife is guided in this region by the formation of an aperture which is arranged in the support.
With a device of this type, the sharpening is carried out by only two shanks, those which have identical counterweights. Furthermore, controlling the cams in an identical manner is not simple, which often brings about a distortion of the sharpening zone, the force applied by each rod not being identical. Furthermore, guiding the blade as it is introduced into the notch of the support is not simple, the blade often coming into contact with the support which renders this blade increasingly blunt and brings about damage to the support. Finally, this device is relatively fragile.
These are the disadvantages which are intended to be overcome in particular by the invention by providing a sharpening device which is particularly simple to use and which has an effective sharpening zone.